The seven participating laboratories share a common interest in understanding the development of the nervous system of Drosophila melanogaster and its relevance to similar phenomena in humans. Individual research areas include the role of homeotic genes in developmental programming, the role of neurotransmitters in controlling the formation and maintenance of the normal structure of the nervous system, the genetic and molecular analysis of the subsets of the genome playing a prominent role in neurogenesis, the molecular analysis of particular genes with major effects on patterns of synaptic connectivity and the identification and characterization of those genes involved in olfaction. All of the proposed experiments are based on the use of mutants to dissect complex developmental process within the nervous system into hopefully simpler events. Our ultimate goal is to characterize the molecular events associated with each of the loci under study. Since many of the basic mechanisms of development are likely to have been conserved during evolution, information obtained about Drosophila, which offers so many advantages for molecular genetics, is likely to be relevant to related phenomena in higher organisms as well.